


Lines Uncrossed (Commissioned Matter of Intent spinoff)

by Ravvi



Category: Undertale (Video Game)
Genre: Ectogenitals, Emotional Abuse, Forced sibling incest, Gaster continuing to be a thoroughly terrible person, Genital Clamps, Incest, Medical Kink, Mind Games, Non-Consensual Bondage, Other, Penetrative Sex, Physical Abuse, Rough Sex, general darkfic themes, noncon, psychological abuse, straitjacket
Language: English
Status: Completed
Published: 2020-01-30
Updated: 2020-01-30
Packaged: 2021-02-27 08:00:15
Rating: Explicit
Warnings: Graphic Depictions Of Violence, Rape/Non-Con
Chapters: 1
Words: 6,207
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/22473736
Author URL: https://archiveofourown.org/users/Ravvi/pseuds/Ravvi
Summary: Alternate timeline where Sans and Papyrus both get recaptured after the escape attempt in the middle ofChapter 13.Mind the tags, and be extra careful for forced sibling incest.Alternate chapter title that was too stupid to use, 'How to Sex for Dummies.'
Comments: 5
Kudos: 4





	Lines Uncrossed (Commissioned Matter of Intent spinoff)

Sans’ body twitched unnaturally, and a strangled whimper slipped past his clenched teeth. Feverishly, Papyrus twisted the glowing, metal collar locked around his neck, looking for a catch, hinges, a visible weak point,  _ something _ , but there was  _ nothing.  _ Not even an indentation where they should be.

“Hold on brother, just hold on,” Papyrus urged, grabbing the collar on either side and trying to wrench it apart. The runes incised into its surface pulsed, making the snow glimmer as Sans struggled for breath. They were cyan, he realized numbly.  _ Sans’  _ cyan. That wasn’t good. 

Hands shaking, he twisted the collar, centering the largest rune between his thumb, index, and middle fingers. He might be able to jam an attack into it, and then use the leverage to physically pry the metal apart. It was risky but Sans was  _ dying  _ and he had to try SOMETHING. 

Teeth gritted, Papyrus raised his free hand, forcing the other to hold the collar steady. He could. Not. Miss. Sans was far too fragile to survive a blow to his cervical vertebrae, and if his aim was off by even a  _ hair- _

“Ghhhkkkkk…” Sans gurgled.

“Step away,” Dr. Gaster said coldly. Papyrus cried out and threw an arm over his head. Bones erupted from the ground, throwing ice and frozen earth skyward as they latched together into a heavy barricade. There was a long pause, and then Gaster began to laugh.

“It was YOU?! How did you…oh my, that is  _ precious _ .”

“No, no no  _ no _ -“ Papyrus muttered as he scooped Sans up out of the snow, stumbled to his feet, and began running into the forest.

“Where are you going, Papyrus?”

Gaster’s voice seemed to echo off of every rock, tree, and fallen log across his path. Papyrus whimpered, hunching his shoulders as pine needles whipped across his face and shoulders like stinging hands.

“Do you intend to let yourself be chased down like a disobedient child?”

Papyrus dug his toes into the snow, pushing himself faster.

“You’re just delaying the inevitable.”

Gasping for breath, he burst through the trees and into a clearing. Gaster appeared out of thin air at the far edge, expression unreadable and hands glowing a deep, ultramarine blue. Papyrus skidded to a halt, looking around wildly as hand constructs formed in the air around him, fingers outstretched.

“Now behave,” he said, and something clicked shut around Papyrus’ neck. 

“NO!” Papyrus screamed, throwing out his hand. Magic rushed into his arm, and a wave of bones shredded the hand constructs that had surrounded him. He pivoted, about to sprint back into the forest when a deep, penetrating cold shot down his spine. His vision blurred, and the world went eerily silent.

“ _ No _ ,” he choked, trying to force his freezing limbs to move. Disembodied hands surrounded him, gripping his arms, cupping the back of his head, and easing him to the ground. He twisted his shoulders, trying to throw them off, but the movement was sickeningly weak. Terrified, he gripped Sans with what strength he had left, curling around his body in a last, instinctive effort to protect him. 

There was a long moment of silence as the cold crept steadily across his chest. Then, something gently tipped his face upward. Papyrus could barely feel it. His vision had nearly gone dark, and Gaster’s indifferently curious expression was somehow impossibly high above him. It was a struggle just to breathe.

“I underestimated you,” he murmured, running a thumb over his cheek. Papyrus tried to scream, but a choked whisper was all that made it out as Sans was torn from his grip and the world went dark.

===

Gaster calmly pulled his subjects apart, then laid Sans on his back and tipped his face upward. He wasn’t breathing, and his joints felt so loose that it was a wonder the more delicate parts of his hands and feet hadn’t fallen apart. Careful not to jostle him, Gaster thumbed over the suppression collar’s runes, deactivating them one by one until Sans arched and sucked in a ragged breath. His face flushed, and he coughed feebly, falling still as his breathing settled into an uneasy, but steady rhythm.

“And you,” Gaster murmured, repeating the same procedure on Papyrus’ collar. “I didn’t think you had it in you.”

He deactivated the seventh rune, and Papyrus took a shallow breath. His eyesockets fluttered open, and he clumsily tried to sit up. Gaster quickly pushed him back down and reactivated the last rune. Papyrus stiffened, mouth opening soundlessly before he collapsed into the snow. Unlike Sans, his face was still abnormally pale, and he was barely breathing. That was unfortunate, but not wholly unexpected. Papyrus’ soul spent most of its magic on his physical body, so much so that mobility was highly prioritized. It was probably impossible to deprive him to the point of incapacitation without risking permanent damage. And while Gaster was certainly annoyed with his behaviour, he was still valuable. Injuries to assets should always be carefully, and intentionally inflicted.

Gaster stood, directing his constructs to gather Sans and Papyrus together for transport. Their escape attempt may have failed, but it had also severely disrupted his afternoon. He needed to discourage such behaviour, in a manner befitting its execution.

“You two insist on being close with each other,” he mused, placing a hand on Sans and Papyrus’ shoulders as he prepared to teleport. “Perhaps it’s time that your bond was put to better use.”

===

“AAAHHHH **HHHHHHHH** !”

Liquid fire poured through Papryus’ body, searing him from the inside as his own magic slammed back into place. Every fiber of his being was filled to the point of stinging, until he was sure that he would split into tiny, charred fragments from the heat and pressure. He writhed in agony, spine arched as unbearable pain gripped him for an unknowably long time, before finally,  _ mercifully _ fading. His scream choked off into a harsh, hacking cough, and he instinctively tried to roll onto his side.

“I thought that was going to hurt,” Gaster said drily as a set of restraints pulled tight, forcing him to remain supine with his hands at his sides.

“Hhhh-“ Papyrus flinched as a thumb lifted his right eyelid and shone a blindingly bright light into his eye.

“But then, you  _ have _ been excessively stupid. Even by the standards that I have come to expect of you.”

Papyrus cringed, blinking away tears as his other eyesocket was examined. “Too bright,” he gasped, mouth heavy and half numb. His arms, legs, pelvis, and most of his spine were tingling sharply, like he’d sat on his entire body wrong and it had fallen asleep. “Hurts…”

“Yes. Your extremities may have also lost some sensation.”

Papyrus heard a bony hand drag its phalanges along his intercostal spaces. He flinched, but the painful, tooth-gritting scrape barely registered over the burning tingle of resettling magic.

“Luckily, your body appears to have held up,” Gaster said in an amused tone. “In fact…” A hand construct appeared over his midsection, then inquisitively cupped the space between his legs. Papyrus squealed, jerking away as he automatically reached for his magic. The restraints snapped tight, and his plea for defense fell into that terrifyingly familiar, and implacable void. His magic was gone. 

“You’re blushing. Do you find this erotic?” Gaster asked curiously.

“NO!” Papyrus wailed, legs trembling as a fingertip slowly rubbed the notch over his pubic symphysis. 

“The fuck are you doing?! Leave him alone!” Sans yelled from somewhere nearby.

“Your brother is very concerned about your wellbeing,” Gaster smiled thinly. A second hand construct flitted over and disappeared between his legs. He felt it gently run a fingertip around the inner arch of his ischium. “He was excessively verbose about those concerns as well. I eventually threatened to gag him.”

“Sto-haaAAA! S-stop… _ please _ ,” Papyrus begged quietly. The construct stroking his ischium slipped teasingly into his pelvic inlet and formed a loose fist, putting light pressure on the entire rim of his pelvic inlet. It tingled sharply and he reflexively jerked his hips upward, legs trembling as the gentle stretch mixed with his body’s confused, half-numb sensations.

“FUCKER! IF YOU TOUCH HIM, I SWEAR _ , I WILL  _ **_KILL YOU_ ** _!“ _

“You should still be numb. Or at least disinterested,” Gaster mused as the construct began to rock back and forth. “Especially after dispelling a heat. What on earth did Sans do that kept you this naive? Do you even know what an orgasm is?”

Papyrus closed his eyes and took a single, shuddering breath. Sans screamed, and the sound of someone thrashing against restraints filtered through the wall.

“This is why siblings shouldn’t rear one another,” Gaster said, smile deepening as Sans’ incoherent curses echoed through the open door. “We’ll correct that soon.”

The constructs molesting him vanished, leaving him suddenly, and completely untouched. Without another word, he turned, and walked out of the room. 

Papyrus relaxed into the mattress with a halting exhale, ischium and pubic symphysis throbbing. It wasn’t as bad as being in heat. NOTHING was as bad as being in heat, but it still  _ hurt _ and his magic was gone, and he couldn’t  _ do  _ anything about it _ … _

“S-sans,” he whimpered inaudibly, clenching and unclenching his hands as he forced back tears. “Sans? Are you there?”

A rustle filtered through the wall that the bed was pushed up against. “Y-yeah. Yeah Paps. I’m here.”

“I…” Papyrus’ voice broke and he sobbed, shoulders shaking as he pulled himself into as much of a ball as he could. “He put the blocker back in.”

“I know,” Sans said, voice shaking.

“I HATE BEING TIED UP,” Papyrus howled, giving his restraints a single, frustrated jerk.

“He left you…” Sans swore under his breath. “Fuck. I’m sorry.”

“IT ISN’T YOUR FAULT SANS.”

“I know. ‘m sorry anyway,” Sans said with a half-hearted chuckle. “I just…We were so  _ close.  _ And I feel like…I don’t know. Like it’s kinda my fault, somehow. Like there’s something I could have done, or something I should have done?”

Papyrus took a few deep breaths, face turned toward the wall as he closed his eyes. He could almost see Sans’ blandly cheerful expression slipping for a moment into hopeless exhaustion as he snorted dismissively.

“Whatever,” he continued tonelessly. “It doesn’t even matter now. You…just know that you don’t deserve any of this, and I wish…god, I just  _ wish _ -”

His voice broke, and he took a long, shaky breath. Papyrus awkwardly wiped his face off against the mattress. The pins and needles were starting to ease, leaving him feeling weak and a little sore. 

“It does matter, and YOU don’t deserve this either,” Papyrus replied softly, glaring up at the ceiling. “I know for a fact that you didn’t do anything wrong.”

Sans laughed harshly. “Ohhhh, a few choice events come to mind. Karma has a way of collecting its debts, and I was too goddamn lazy to make the interest payments. Guess it’s all come due.”

Papyrus blinked, slightly concerned by the flat, hopeless tone of that last sentence. “That’s not how karma works.”

Sans sighed. “Yeah. Guess you’re right.”

There was a long, still silence. When he focused, he thought he could hear Sans quietly breathing through the wall.

“…what’s going to happen to us?” he finally asked. For a long moment, Sans didn’t respond. Papyrus started to think that he’d spoken too quietly for him to hear.

“Nothing,” Sans finally said, voice dangerously calm. “ _ Nothing _ is going to happen. I’m gonna get you out of here.”

“Sans…”

“I don’t know  _ how _ yet, but that bastard has already made one mistake…”

“Sans, you c…”

“I WILL figure something out, I promise. Y-you just hang in there…”

“ _ Brother _ . You can’t keep that promise,” Papyrus interrupted quietly.

“I…” Sans voice broke again, before dissolving into muffled, angry sobs. “I-I’ll try anyway,” he managed. “I’m s-sorry.”

“Don’t be sorry,” Papyrus said, anger creeping into his tone. This was _exactly_ like Sans, trying to solve everything by himself when now, more than ever, he NEEDED HELP. “And don’t you DARE think that I’m just going to sit around while you’re trying to save us. WE are going to figure something out. WE are going to get out of here, and WE are going to hang in there. Not just me. BOTH OF US.” 

Sans was silent. Papyrus turned his head and thumped his knuckles against the wall. “Do you hear me? I said  **BOTH** of us. That’s  **NOT OPTIONAL** . Ok?!” he demanded, punctuating each word with another thump.

“… _ ok _ ,” Sans finally whispered.

“Good,” Papyrus replied with a short, shaky sigh. Good. He felt a little better. If they ever got out of here, (and that IF was looking bigger and more hideous by the second), then he would rather die than leave Sans trapped here alone. He didn’t want the idiot to think that sacrificing himself was in any way acceptable, or that Papyrus was going to sit around like…like some damsel in distress…

“YOU again?” Sans said, so abruptly that Papyrus jumped. “Don’t you ever sleep?”

“Is that really relevant to your current condition?” Gaster asked coolly.

“Is your FACE really relevant to your current condition?” __ Sans mocked. 

“I’m beginning to suspect that you  _ like  _ being gagged,” Gaster noted drily.

“I’m beginning to suspect that you  _ like _ being a psychopath. You should take a load off, you know? Take up a hobby, learn a new skill? You could always go stick your dick in a blender, or jumping off of tall build-mmmph!”

“You certainly look as though you’re feeling better,” Gaster said mildly.

Sans yelped in shocked outrage, and Papyrus jerked against the restraints, instinctively trying to rush to his aid.

“If I were you, I’d save that energy. You’re going to need it.”

“Mmnghk kkww!” Sans spat past the gag.

“How is it that I can still understand you? One of these days I must find a way to permanently silence that mouth of yours…” Gaster mused, footsteps retreating back down the hall.

It was deeply quiet for a very long moment, but when he focused, he could still hear someone breathing through the wall. Maybe...

“Sans?” Papyrus whispered, touching the wall pleadingly with his fingertips. “Brother?”

Nobody answered. It must have been his imagination.

===

Papyrus had never been good at doing nothing. Being stuck indoors for more than a few hours left him pacing and obsessively cleaning every surface he could get his hands on. Being locked in a laboratory for the past (few months?) had desensitized that impulse, but not to the point where he could calmly lie on his back for more than a few minutes with nothing to do. He fidgeted, rolling his wrists and ankles in their restraints. He flexed his spine and legs, exerting his returning strength against the cuffs with the hope that their tie points would eventually fray. He let this simple escape become a puzzle, pushing aside the anxiety as minutes ticked by and Sans didn’t return. Gaster still needed them both. If he didn’t, he wouldn’t have brought them back at all. He NEEDED them, and that’s why Sans was going to be…going to be…

He folded his thumb tightly into his palm and wrenched on his hand with a pained grimace. The cloth strap between his radius and ulna jerked taut, preventing him from simply tugging his hand free. It felt a little looser, but the inside of his wrist was getting quite sore. Perhaps if he worked at it more carefully…

Another (thirty minutes?) slipped by. The mattress beneath him became wrinkled and sticky with sweat, so he took a moment to ineffectively tug it smooth with his bound hands. His pinky and ring fingers were still numb, and the entire side of his arm tingled when he moved them. It was irritating.

He’d only just gotten the mattress into an acceptable state when he finally heard Gaster’s footsteps approach the bed.

“You need us for something,” he said, immediately falling still.

“Has this only just occurred to you?” Gaster asked mildly. A hand construct appeared above his face, then reached down to unfasten the strap around his neck.

“N-no. It just…” Papyrus trailed off, unsure of why he’d thought that this was so important.

“You are not required to understand your purpose. Only to serve it. Sit up,” Gaster said, directing his constructs to unstrap his wrists and ankles. Cautiously, Papyrus sat, unable to resist stretching a little as that awful ache between his shoulder blades and lower back finally eased.

“Is there any lack of sensation in your hands or feet?”

Papyrus mutely flexed his fingers, noted that the last two fingers on each hand were still numb, and shook his head. 

“I see. Come with me.”

He silently obeyed, following as Gaster lead him down the hall and into the lab. The doors that he had smashed earlier had been swept away, and the hinges had been removed from the empty door frames. Each little room looked identical, with a neatly made bed, a chair, and a simple end-table enclosed between four, claustrophobically close walls. Papyrus found himself numbly wondering how many people Gaster had kept trapped here before his own capture. Four? Five? There were at least that many rooms.

They reached the lab, and Gaster closed what looked like an unpainted, spare door behind them. He waved a hand, and then a pair of hand constructs flitted over to Papyrus, firmly grabbed his wrists, and guided them over his head. 

“Nnnn-” he whimpered softly as they cuffed them together, then hooked the cuffs to a tether already looped through a large eyebolt in the ceiling.

“On your toes,” Gaster instructed. Papyrus inhaled sharply as the command was reinforced by an insistent, upward tap between his legs, quickly rising onto the balls of his feet. The constructs secured the tether, leaving him stretched out in the middle of the floor. Gaster slowly circled around behind him, and Papyrus forced himself to take a deep breath, fighting down the alarming sense of how vulnerable his body was in this position. If there had been any doubt that this was going to be a punishment of some sort, it was completely gone now.

“Are you familiar with vibrators?”

Papyrus shook his head again, panting softly as he took a few, tiny steps to maintain his balance. He wasn’t going to scream, even if it hurt, he wasn’t, he wasn’t, he  _ wasn’t- _

“I suppose that isn’t terribly surprising. Batteries are difficult to find, and often spoiled by wet conditions. Even if you’d come across one, you wouldn’t have been able to do anything with it.”

A thin, mechanical buzz began to emanate from the air in front of his midsection. Papyrus snapped his head down, and saw a hand construct holding a short, black baton with an egg-shaped head near his crotch. It began to move toward him and he flinched away, only half suppressing a shriek of alarm. 

“Oh, for pity’s sake,” Gaster muttered, flicking a hand. “This is  _ not _ going to hurt.”

“Mnnn,” Papyrus whimpered as a set of hand constructs seized his ankles and forced his legs apart. He barely had time to regain his balance before an intense, thrumming pressure rolled over his pelvic inlet.

“AHH!” he cried out, spine arching ineffectively and toes pressing into the floor as warm flutters rippled across his pelvic girdle. “O-ohhhh…”

“You see?”

Papyrus bit down on his tongue with a quick, shuddered breath, trying not to scream for an entirely different reason.

“One must, of course, take care not to numb out the stimulated areas,” Gaster continued as the hand construct ran the vibe down his tailbone, and then over his pubic symphysis. Papyrus choked, knees shaking as pressure rapidly built, before releasing itself in a single, intense torrent. Wetness gushed down his legs, and he gasped for breath, moaning weakly as the vibrator moved back over his pelvic inlet. The hand holding it was splattered with vivid orange fluid. He watched in dazed fascination as it dripped to the floor in shimmering, wet strands. Such a mess...

“With you, it’s barely seems necessary though.”

A second hand appeared, holding a small, silicone egg. It slipped inside his rib cage, and Papyrus squirmed with alarm, breath hitching unevenly as it ran its fingers down the sensitive underside of his sternum.

“N-no...please d-ohhhHHHHHH!” Papyrus wailed, unable to silence himself as it turned on the vibrator and rolled it over his sternum. Magic rushed down his spine, oozed over the surface of his pelvic girdle and dripped onto his feet. He panted fitfully, eyes sueezed shut as the pressure inside his chest built and built and built…

“Good boy,” Gaster said as Papyrus cried out, and his soul flickered into being. The hand construct behind his ribs quickly caged it and drew it out into the open. 

“You’re healing very well,” Gaster finally said. Haltingly, Papyrus opened his eyes, staring helplessly as Gaster carefully turned his soul between his fingers without touching it. The soft, pillowy heart had a dark indentation in its center, a flaw in the otherwise perfect construct. A part of him wanted to be horrified by that in a deeply fundamental way. Instead, he stared at it, trying to feel…something. Anger, sadness, or even a sense of outrage. But no. He simply felt distant and detached. He already knew what to do about it, after all. He knew the reason why his magic had abandoned him, and there was only one way that he could let this end.

He would not fail a second time. 

“... see what your magic wants to form…” Gaster was saying.

“AH!” Papyrus cried out, numbness shattering into sudden terror as Gaster pressed a finger against his soul. Something inside him connected for the briefest of moments, and then the magic inside his pelvic girdle solidified with an abrupt, aching pinch. Papyrus stared down at himself, chest tight as tears welled up behind his eyesockets. The contact had lasted for less than a second, but the cutting, clinical feeling of Gaster’s touch lingered, leaving him deeply unnerved. He ground his teeth together, forcing the feeling beneath his own, bubbling anger. This was nothing he didn’t already know.

“What on earth…?” Gaster muttered, releasing his soul, then pressing his thumb into the top of the construct that had formed between Papyrus legs. The vermillion ectoflesh moved readily, maintaining its soft, protective shield over his pelvic inlet and sacrum. A row of five, simple nodes ran down its center, each providing a small point of pleasure that he had used for…for himself. Papyrus closed his eyes, face burning as the brief comfort of letting his soul dissipate soured into angry mortification. He’d never let anyone see this. He’d never WANTED to let anyone see this. It was  _ private _ , and certainly not something he’d ever intended to share. 

“This is ridiculous. Were you educated by peeking beneath the skirts of children’s dolls?”

Papyrus trembled, throat so tight he couldn’t speak as Gaster critically ran his finger down the center of the shield, then pushed upward on it in a mildly unpleasant way.

“For god’s sake, this is almost offensive,” he muttered to himself. “You’ve scattered the nerves and completely neglected any sort of lubrication or ejaculate. And I thought Sans was damaged.”

He held out a hand. A construct dropped a syringe into it and Papyrus cried out, throwing himself backward in sudden, irrational fear.

“Stop that,” Gaster said dismissively, hooking two fingers around his pubic symphysis and holding it firmly. “And pay attention. This will become your imprint, and you will have to actively focus to form something else.”

He uncapped the syringe with his teeth, then sank the needle into the center of the shield and pressed the plunger. Papyrus screamed, spine arching in shock and revulsion as the liquid shot inside him with an alien, cramping pressure. Gaster sighed impatiently, then flicked his hand. A hand construct roughly grabbed the back of Papyrus’ head, while a second shoved a rubber wedge into his mouth.

“For pity’s sake, you’d think I was murdering you,” he growled as the constructs strapped the gag into place. “Now  _ relax _ .”

Papyrus whimpered fitfully, resisting the urge to draw one of his knees up to his chest as Gaster placed two, glowing fingers over the injection site. He held them there for a moment, then slowly drew them forward. The fluid moved with them like iron filings to a magnet, twisting inside his body in a severely unsettling way. 

“At least you’re still pliable,” Gaster muttered, curling his fingers inward toward his palm. Papyrus doubled over with a pained grunt as the fluid followed, pulling the ectoflesh containing it outward. The cover over his inlet slid off, robbing material from inside his pelvic girdle to create a heavy, pendulous shaft. The nodes slipped forward into the tip, which flared into a deeply pronounced head. A line of small ridges formed behind it, sweeping backward in gentle V-shapes that pointed away from his body. What little was left slipped backward to coat the upper edges of his pelvic brim, anchoring the ridiculous thing tightly to his pubic symphysis and giving it some much-needed structure.

“Much better,” Gaster muttered, giving the appendage a stroke. Papyrus jerked under the touch, shocked and dismayed by how sensitive it was.

“Do you know what this is?” Gaster asked him as the constructs let go of his ankles. Papyrus stumbled onto his toes, giving his aching wrists a slight reprieve as he tearfully shook his head. The shaft bobbed between his legs, so tight and engorged with magic that fluid was leaking out of the tip. It looked fundamentally wrong, sticking out from his body like a bizarre, swollen finger. For an absurd moment, he was completely sure that it was going to fall off. 

“I thought as much,” Gaster muttered, rolling his fingers. Something pressed into Papyrus’ lower back, and then a hand construct drew a thick, cloth strap around his lumbar vertebrae. “This will prevent us all from having to sit through a few hours of awkward fumbling. Just relax, and it will guide you through the motions.”

Another set of straps were pulled over his upper femurs, and then everything was cinched tight, leaving him strapped to the front of something that felt ominously cold. Papyrus craned his head back to try and see what it was, then snapped his gaze forward again when a door opened at the far end of the lab.

“Mmngh!” he cried out, shamefully drawing his knees together as Sans was dragged into the room.

“Don’t be shy now,” Gaster cooed, tipping Sans’ face upward. He irritably jerked his chin away, staring furiously at the floor with tears in his eyes. He was gagged, and a heavy, white straitjacket was wrapped around his torso, pinning his arms around his body in an obscene facsimile of a hug. Cyan magic glimmered between his legs. Papyrus stared pleadingly at him, trying to see whether he had been hurt in some way. 

“Sans has quite a bit more experience than you, but he didn’t come by that knowledge gracefully,” Gaster said, one hand placed infuriatingly beneath Sans’ chin as the constructs set a high-backed chair and a step-stool in front of him. “I’ve corrected the physiology, which you can see…”

Gaster released him, and the constructs grabbed his shoulders, dragging him up onto the step-stool. They bent him face forward over the back of the chair, spread his legs, and shoved his head down. Papyrus stared at the construct enveloping Sans’ pelvic inlet, simultaneously horrified and fixated by this profane violation of privacy. It was much more similar to Papyrus’ shield than this ridiculous shaft, but UNLIKE his shield, there was an oozing slit in the center, surrounded by a pair of soft, pillowy mounds with a large node at their peak. The entire thing was translucent, revealing a familiar, ridged pattern of swept V-shapes inside a narrow pocket. 

“This is a vagina. The outer parts form the vulva, with labia, and clitorous,” Gaster said, indicating each part as the constructs strapped Sans’ ankles into place. “Your construct-“ 

Sans lurched to the side with a muffled scream, almost overturning the chair and throwing himself to the ground.

“That is  _ enough _ ,” Gaster spat with a sharp gesture. A pair of constructs gripped Sans’ shoulders, while a third fetched a tray from the counter. Emotionlessly, Gaster selected a small, silver clamp from it, and affixed it tightly to one of Sans’ labia.

“MMMNGH!” Sans yelped, body twitching through a half-aborted jerk as Gaster held the clamp between two fingers.

“Continue to struggle if you like, but the next step will be piercing,” Gaster said darkly as he attached a second clamp to the same labia, then threaded a piece of black cord through each. “If done correctly, it creates a permanent hole that becomes part of your imprint.”

Sans sobbed furiously as he affixed two clamps to the other labia, and tied a piece of cord to each.

“Of course, I may not stop at your labia. The clitoral hood is an especially compelling restraint point,” he said dispassionately. “I find subjects are rather disinclined to struggle against it.”

Sans spat something nasty through the gag, shoulders tensing and arms struggling fitfully against the straitjacket as Gaster tied the cord around Sans’ own, spread femurs and back to the chair. Then, he tightened them. pulling the labia agonizingly apart until Sans’ entrance had the cruel likeness of a butterfly. Papyrus stared at it, breathing oddly hard as the hand constructs carefully began to move the chair and the stepstool toward him. It looked like they were lining things up with…

They briskly rubbed the tip of his shaft and pressed it lightly against the outside of Sans’ entrance, right over the pocket. Oh god, they were going to put him  _ inside _ …

Papyrus jerked forward with a muffled cry, shaft skidding downward as liquid spurted out of it in a single, powerful squeeze. It splattered on the chair between Sans’ legs, dripping to the floor in glistening, vermillion strands. 

There was a short silence, broken only by Papyrus’ disjointed gasps for breath. Then, Gaster began to laugh.

“Dear god, I wouldn’t have thought that  _ stamina _ , of all things, would be an issue for you,” he chuckled. “Can’t you control yourself?”

Papyrus whimpered softly behind the gag, eyes fixed on the horrible, alien shaft attached to his body. Tears streamed down his face as it drooped between his legs, throbbing and so sensitive that even the air running over it was almost too much to bear. He wanted this to be over. He wanted to lie down, crawl under a blanket and shut out the world.. _. _

“I suppose that is a bit much to expect. At least we know you’re functioning properly.”

A hand construct wrapped its fingers around the shaft and gave it a rough stroke. Papyrus twisted in the cuffs, gurgling in overstimulated misery as saliva ran down his chin and the shaft gradually began to stiffen again.

“Good boy,” Gaster said, selecting a thick, black band from the tray. “Now let’s give you a bit of help…”

He worked the band onto his fingertips, spread it out, and carefully worked it over the head of Papyrus’ construct. Carefully, he threaded it over the shaft and down to the base. Once there, he flexed his fingers, letting it roll off. It snapped taut against his pubic symphysis and Papyrus screeched, exhaustion immediately dissolved by the excruciatingly intense pinch.

“That should do,” Gaster nodded as his shaft quickly swelled past the band, locking it into place. “Now, let’s try this again.”

A hand construct carefully pressed the tip of his cock against Sans’ entrance again. Papyrus stumbled, feet skidding on the wet floor as something behind him whirred to life, and his pelvis was slowly pushed forward. Sans screamed in protest, legs jerking brokenly as the shaft was pushed inside, stretching him out further than Papyrus would have thought possible. It was tight, and so  _ hot _ . He gasped unevenly, body jerking through something that almost felt like a second orgasm as the machine slowly drew him back.

“Relax,” Gaster prompted, and then the machine shoved him forward. Papyrus screamed through the gag, unable to do anything  _ other  _ than relax as he was plunged into Sans’ entrance again, and again, and again. He had no control over the angle, speed, or depth, feet helplessly pushing with what little traction he had to keep a little weight off of his burning wrists. The ridges on his and Sans’ constructs rubbed and caught against one another, creating an intense, vibrating friction that even Sans’ indecent amount of slippery wetness couldn’t ease. It quickly stoked the pressure to a torturous level, leaving him teetering on the brink with no method of release. Beneath him, Sans moaned and jerked, entrance twitching fervently before squeezing rapidly around him in a way that was outrageously erotic. The machine forced him to continue thrusting, even as he felt Sans’ passage suddenly grow tighter and shorter, and the tone of his voice changed from desperate moans to squeaks of discomfort.

“Remember what this looks like,” Gaster said softly. “Remember how he started to hate you, by the end…”

Papyrus wailed and shut his eyes as the machine began to push him faster, plunging him in and out of Sans at a punishing depth with sloppy, wet slaps. Sans screamed, and wetness spurted over Papyrus’ cock, drenching the floor with cyan fluid as he came again.

_ I’m sorry, I’m sorry, I’m sorry _ , Papyrus howled to himself, over and over as the pressure filled his mind, leaving him unable to think about anything else. Unconsciously, he began to push into each stroke instead of fighting it, adding his own weight to the deep, steady thrusts. He was distantly aware as Sans came a third time, and then a fourth, before the pace finally slowed. He trembled uncontrollably, shaft aching fiercely beneath the ring. More than anything, he  _ wished _ that it would somehow pop off.

Gaster said something smugly, and the machine drew him part-way out of Sans. A hand construct wrapped its fingers around his dripping shaft, while a second began to work a small, plastic hook underneath the ring. It had become buried in the construct, which was so swollen that Papyrus would have barely been able to fit his hand around it. He stared, wondering distantly how Sans hadn’t split apart under the strain.

The constructs snipped the ring free, and Papyrus howled with desperation and pain as it was peeled off. He shoved himself back into Sans, who jerked forward with a despairing, overstimulated plea. Papyrus could barely hear him as the pressure  _ finally _ released, spurting hot magic deep inside Sans’ pocket, while the shaft slowly began to soften. Papyrus dangled from the cuffs, hands numb and body utterly drained as he feebly watching a rivulet of orange fluid ooze down the inside of Sans’ femur.

“Remember this, the next time you decide to plan an escape,” Gaster said softly as Papyrus forced himself to look away. 

===

The constructs brusquely sprayed him off, then dragged him into a room. Sans was already there, still dripping wet from his own perfunctory shower. He stiffened, eyelights shrinking down to tiny pinpricks as Gaster directed his constructs grab Papyrus’ wrist and drag him forward a few steps. Silently, they cuffed his right hand to Sans’ left, before cuffing Papyrus’ free hand to the bedpost. Job done, they vanished, and Gaster left the room.

Sans jerked away the second that they were alone with a thin, animalistic cry. Papyrus yelped, abused wrist burning as his arm was yanked forward and the steel cuff dragged across it. Sans looked up at him, panting as his eyelights slowly dilated to a more normal size. Then he looked down at the handcuff, swallowed hard, and looked back up at Papyrus. His mouth opened and closed soundlessly for a moment before he finally shut it tightly, body tense and free arm drawn tightly across his chest as tears ran down his face.

Papyrus slowly collapsed to the floor with his arm still outstretched, too tired to cry, and too overwhelmed to deal with what had just happened. A part of him was sure that he’d betrayed Sans in the worst possible way. He was sure that there was SOMETHING he could have done that would have made this easier on both of them, and that a part of this whole, sickening ordeal was his fault. 

If Sans wanted to hate him now, that would be ok. He already hated himself.

Slowly, the cuff went loose. Sans sniffed loudly, and then a cold, trembling body pressed against his. Papyrus let his head fall forward, chest hitching with weak, desperate sobs as he realized that, even though there was nothing he could do to make this better, Sans still loved him.

Letting his chin fall to his chest, Papyrus leaned slightly into Sans’ body, staring numbly at the floor as the rest of that silent, awful night slowly passed.

**Author's Note:**

> There is a terrible part of me that went 'wait, if it's been commissioned that Papyrus be strapped to a sex machine that's forcing him to do all this, then isn't he going to struggle and mess everything up and stuff?' which was then answered 'nOt if hE hAs to sTanD on hIS tOES' >:9
> 
> Curious about commissions? More info [here.](https://www.pillowfort.social/posts/283525)


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